Temperature Dependence of Very High Temperature Vacuum Tensile-Fatigue and Tensile Strengths in Drawn Tungsten Wire

Abstract

Tensile-fatigue and tensile tests of drawn tungsten wire (diameter 0.30 mm : JIS-H4461. VWW1-D) at very high temperature (800-2700°C) in vacuum (pressure 10^-5 mmHg) were made using a very high temperature vacuum tensile-fatigue tester of electrical current transite heating type [J. JSMS, Vol. 16 (1967), P. 89]. And temperature-dependences of fatigue and tensile strengths were studied. The main results obtained are as follows : (1) According to the increase of testing temperature, the tendency of necking in the specimen becomes weak and the deformed range increases. (2) Relation between testing temperature T and tensile strength σ_o to cause the fracture is expressed by log₁₀ [σ_o (kg/mm²)]=AT+B, A=-6.7×10^-3oK and B=2.40. (3) Relation among testing temperature T, cyclic stress σ and the number N of stress cycles to cause the failure is expressed by log₁₀N=αT+βlog₁₀[σ (kg/mm²)]+γ, α=-3.56×10^-3oK, β=-3.4×10^-3, and γ=1.45.